6 Answers
6

There's a product called Plasti-Dip that used to be carried at Harbor Frieght along with most hardware stores. I was a liquid vinyl used for coating tool handles. It dries to a soft grippy texture and comes in colors.

Find more twine or rope (looks like a natural sisal) that matches the "laces" on the shoes. Wrap the twine around the posts in a spiral until they are completely covered. You will probably need to glue the twine occasionally, and perhaps rough up the paint so the glue sticks.

The twine in the picture looks like it is waxed. I would make sure to use non-waxed if you are going to wrap the posts, otherwise the towels would still probably slip right off.

Cheap fix: Get a heavy, wide rubber band and wrap it around the middle of the ball. The wider the better, to prevent it rolling off.

Caveats: Rubber bands decay over years, and if you leave it on until it breaks you may find some rubber stuck to the surface. This could also trap water, allowing mold growth. I haven't tried it myself.